Apr. 22, 2017, 4:11 p.m.

After the official marching part of the March for Science was over, some attendees headed over to the science expo at Pershing Square, which was kind of like a big science fair.

The event was scheduled to go until 4 p.m., but by 2:45 p.m. most of the people running the booths were feeling pretty done. It was hot out there!

Along the way, I met some Caltech graduate students teaching kids how to make solar panels with sunscreen and blackberries: the blackberry juice absorbs sunlight, while the titanium dioxide in the sunscreen converts the sun's photons to electrons.

Apr. 22, 2017, 1:45 p.m.

In its approach to scientific research, President Trump’s budget can be accurately described as a mugging. I’ve watched this happen before, up-close and personal. It does not end well.

In 1979, President Carter set an ambitious but achievable goal to get 20% of the nation’s energy from renewable sources by the year 2000. I then headed the federal Solar Energy Research Institute, which spearheaded the Manhattan Project to Harness the Sun. In the late 1970s, the United States had more PhDs in the solar field, filed more solar patents and made more commercial solar modules than the rest of the world combined.

In its first year, the Reagan administration slashed the solar institute’s staff by 40%, reduced its budget by 80% and abruptly terminated all of its 1,000-plus university research contracts (including shutting down work by two professors who later won Nobel Prizes). The firings were so wantonly brutal that many of the researchers were driven into other fields. The consequences have been huge.

Scientists and their supporters took to the streets of Washington and other cities around the world Saturday, with many expressing worries about a diminishing role for fact-based research under the Trump administration.

Waving signs with slogans like “Science is Real” and “Ask for Evidence!” the marchers gathered at the base of the Washington Monument. The crowd swelled by the thousands even as a light rain turned to a downpour.

Organizers encouraged participants to wear work gear such as their lab coats, or to dress as a science hero. Nancy Davis of Baltimore came wearing Revolutionary War-era regalia as Benjamin Franklin. She said her chemist sister approved of the tribute to the Founding Father and part-time electricity experimenter.

Apr. 22, 2017, 12:53 p.m.

Kimberly Prado, left, and Morgan Hatch donned the lab coats they wear to work for the L.A. March for Science. (Deborah Netburn / Los Angeles Times)

Spend a few minutes taking in the crowd at the March for Science L.A. and a few trends emerge. There are a lot of planetary models, a lot of signs that say "I'm with Her" pointing to Mother Earth, and a whole lot of white coats.

I'm a sucker for tools of the trade (after 18 years working as a journalist I still can't believe I get to carry around a reporter's pad for work — so official!), so I wanted to know if the white coats were real.